| Plot | Easiest | Most Difficult |
|---|---|---|
| Plot 1: Sorted Pie Chart | 0 | 0 |
| Plot 2: Unsorted Pie Chart | 0 | 0 |
| Plot 3: Filled Bar Chart | 0 | 0 |
| Plot 4: Bar Chart | 0 | 0 |
| Plot 5: Unsorted Scatterplot | 0 | 0 |
| Plot 6: Sorted Scatterplot | 0 | 0 |
| Plot 7: Colors | 0 | 0 |
| Plot 8: Area | 0 | 0 |
Aesthetics (encodings)
PH345: Winter 2026
Farbtafel, Paul Klee (1930)
Which color appears most often?
Tidied up Farbtafel, Ursus Wehrli (2003)
Which color appears most often?
Case study: Five proportions
One proportion for each of five groups (A-E)
Guess group B’s numerical value as a proportion, e.g. 0.98.
Your answer would probably be close to 0.28
For each of the next 8 plots, guess group B’s numerical value based on the plot. Enter your guesses on this google form:
Plot 1: Sorted Pie Chart
Plot 2: Unsorted Pie Chart
Plot 3: Filled Bar Chart
Plot 4: Bar Chart
Plot 5: Unsorted scatterplot
Plot 6: Sorted scatterplot
Plot 7: Colors
Plot 8: Area
Truth minus Guess (Bias)
Relative order of accuracy
Take away: some aesthetics communicate data better than others
Figure 14 from Mackinlay (1986)
Bang Wong
Vertex Fellow, Data Visualization at Vertex Pharmaceuticals.
Formerly Creative Director of the Broad Institute of MIT and adjunct assistant professor in the Department of Art as Applied to Medicine at Hopkins
Published monthly column on data visualization in Nature Methods journal from 2010-2012
Example 1
Different visual variables encoding the same five values.
Figure 1c from Wong (2010a)
Example 2
What is the rate of change of atmospheric CO2 over time?
Figure 6 from Cleveland and McGill (1985)
Example 3
What is the relative size of big vs small circle?
14x
How does distance between lines vary?
it’s constant
Figure 1c from Wong (2010a)
Aesthetics for different types of data
Figure 15 from Mackinlay (1986)
Point out the swap between Quant and Ord in (length, angle, slope, area, volume) and (density, color saturation, color hue, texture, connection, containment), and then (hue, texture, connection, and containment) further improve between ord and nom.
Example 4
Lines in graphs create clear connection. Enclosure is an effective way to draw attention to a group of objects.
Figure 2b from Wong (2010b)
Example of shape as grouping for nominal data, but connection (on the rhs) provides even better grouping. but enclosure can counteract this connection, if needed
Example 5
What regions of the US experienced greatest population growth?
Figure 4.2, Wilke (2019)
Key point is that color is much more effective when used to group observations rather than for numbers
Example 6
How do Malawi’s teachers positive teaching practices compare to those of other Sub-Saharan African countries?
Figure 3.2, Asim (2024)
Another example of effective use of color – here a distinctive color is used to frame the country we are interested in, Malawi, and the other countries are also colored according to a blue scheme. On the other hand, it’s tempting but wrong to draw meaning about the different shades of blue.
Example 7
How do entrance and pass rates for Primary School Leaving Certificate Examinations (PSLCE) compare between boys and girls in Malawi?
Figure 5.2, Asim (2024)
Example 7
How do entrance and pass rates for Primary School Leaving Certificate Examinations (PSLCE) compare between boys and girls in Malawi?
Figure 5.2, Asim (2024)
Example 8
Toward Safer and More Productive Migration for South Asia
Number of deployments is calculated as average for Bangladeshi, Indian, Nepali, Pakistani, and Sri Lankan labor migrants in their respective top five destination countries… remittances are defined as total amount of remittances that flow into Bangladesh, India, Nepal, and Pakistan.
Figure 3.4, Ahmed (2022)
Phil’s Recreation of Figure 3.4
Plotting lines emphasizes change between points: the change in the annual growth rate. How easy is this to interpret?
Drop the lines
Removing the lines makes the differences less dramatic (probably a good thing)
